Piscine orthoreovirus (PRV) is ubiquitously present in farmed Atlantic salmon and associated with the disease heart- and skeletal muscle inflammation (HSMI); one of the most common viral diseases in Norwegian aquaculture. Although both the virus and disease has been known for many years, there are today no specific interventions directed against reducing PRV and HSMI.
In recent years, new information has been generated to shed light on the prevalence of PRV and link to disease. Until recently, HSMI was considered a problem for Norwegian aquaculture mainly, with a few reports from Scotland. HSMI have now been diagnosed in Canada and Chile as well, and PRV is prevalent also there. In addition, a novel variant of PRV has been found in farmed rainbow trout in Norway, associated with pathology resembling HSMI. Last, but not least, PRV was associated with melanized spots in salmon filets, a problem which has significant economic impact on the aquaculture industry. Much points in the direction that the focus on PRV will increase in the future.
An essential tool in virus research is purified viruses, free from other biological material. Pure virus is important for the study of viral mechanisms. The most common source of pure virus is cell culture, but so far no cell line has been shown to support amplification of PRV to levels suitable for purification. Øystein Wessel from the Norwegian University of Life Sciences have developed a method to purify virus from infected salmon blood, and based on pure virus a recently published study demonstrated the causality of PRV for HSMI (Kochs postulate).An experimental challenge showed that pure PRV alone is sufficient to induce HSMI. This is fundamental information for future research on PRV/HSMI.
Pure PRV also enables functional characterization of the virus, like the study of what it takes to inactivate its infectivity. Pure virus can be quantified in exact numbers of viral particles which allow standardization of experimental challenge studies to compare PRV variants and virulence. In order to understand the complex interaction between virus, host and environment, it is essential to design experiments that isolate single factors and explore the impact separately, like pure virus.
Project manager at NVI
Partners
- NMBU
- VESO Vikan
- Nofima
